System Tables Views Oracle PLSQL

SQL>
SQL> create table foo (a int );
Table created.
SQL>
SQL>
SQL> select table_name, tablespace_name
  2  from user_tables
  3  where table_name = 'FOO';
TABLE_NAME                     TABLESPACE_NAME
------------------------------ ------------------------------
FOO                            SYSTEM
SQL>
SQL> drop table foo;
Table dropped.
SQL>
SQL> create table foo (a int ) tablespace users;
Table created.
SQL>
SQL> select table_name, tablespace_name
  2  from user_tables
  3  where table_name = 'FOO';
TABLE_NAME                     TABLESPACE_NAME
------------------------------ ------------------------------
FOO                            USERS
SQL>
SQL> drop table foo;
Table dropped.
SQL>
SQL>